佛山市农田生态系统的生态损益

农田生态系统是一类半自然半人工生态系统,既具有产品提供、生态缓冲与调节等正效益,也具有水资源消耗、温室气体排放、环境污染等负效益。根据生态系统服务的内涵,运用环境经济学的相关理论,建立了佛山市农田生态系统生态损益评价指标体系,并利用市场价值法、影子工程法、机会成本法、替代市场法等,定量评价了佛山市2000—2009年间农田生态系统服务的生态损益。结果表明,佛山市农田生态系统的生态价值由2000年的58.77×108元上升到2009年73.09×108元,10年间上升了14.32×108元。根据研究期间农田生态系统的生态价值分析,产品提供功能受人类技术和管理的影响较大,具有较高的提升潜力,是佛山市农田生态系统最主要的服务功能之一。产品提供价值占正效益价值比例由2000年的30.47%上升到2009年的61.15%,占净效益价值的比例则从2000年的36.86%上升到2009年的69.33%。可见,除产品提供价值外,佛山市农田生态系统的其他服务功能在逐渐削弱,需引起各部门的高度重视。全市正效益远大于其负效益,且正效益与负效益的差距在逐年扩大,正负效益价值之比由2000年的5.77∶1上升为2009年的8.48∶1。水资源消耗以及温室气体排放是佛山市农田生态系统最突出的生态问题,二者所产生的环境成本在2000年占总环境成本的82.79%,在2009年仍占78.40%。因此,有必要采取有效措施减少农田生产的灌溉用水或改变农田耕作制度以减少其负面影响。佛山市农田生态系统的生态损益研究表明,农田生态系统具有多种正、负生态效益,应该重视对农田生态系统各项生态效益价值的评估,从而实现快速城市化地区自然、经济、社会生态系统的持续发展。     

中国西部冬油菜种植的生态效应评价

为探讨在中国西部推广种植冬油菜的生态效益,以河西走廊4月份的冬油菜、冬小麦、麦茬和春播4种农田地表进行风洞模拟研究.结果表明：冬油菜具有显著的抗风蚀效果,其地表粗糙度可达4.08 cm,起动风速高达14 m·s^-1,而且在相同试验条件下,其风蚀模数和输沙率分别是春播农田的4.1%和485%,其土壤有机质、碱解氮、速效磷、速效钾及土壤过氧化氢酶、脲酶、碱性磷酸酶、转化酶活性和微生物数量等的流失量也仅分别是春播农田的1.4%、5.1%、1.6%、2.7%、9.7%、3.6%、6.3%、6.7%和1.5%.因此,在地表风蚀的我国西部地区研发、推广种植冬油菜,可有效防治农田土壤风蚀,蓄水保肥,并可增加复种指数和经济效益,具有防治土地沙漠化、改善区域生态环境的作用.     

东北地区森林资源生态风险评价研究

根据区域生态风险评价的理论和方法体系,对东北地区森林资源进行了生态风险评价．东北林区生态风险问题形成的主要胁迫包括物理胁迫、化学胁迫、生物胁迫和社会胁迫,其权重系数分别为0．30、0．22、0．11和0．37．东北93个林业局中,轻风险占64．4％,中风险占21．2％,重风险占13．3％。严重风险占1．1％,符合偏正态分布．东北区森林生态风险的地域分异明显,靠近长白山区的森林处于轻风险和中风险等级,向西生态风险越来越重,处于重风险和严重风险等级的林业局主要集中在小兴安岭地区．必须加强东北区风险管理和森林景观的修复与重建。     

Ecological tracers reveal resource convergence among prey fish species in a large lake ecosystem

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Nitrous oxide respiring bacteria in biogas digestates for reduced agricultural emissions

Inoculating agricultural soils with nitrous oxide respiring bacteria (NRB) can reduce N₂O-emission, but would be impractical as a standalone operation. Here we demonstrate that digestates obtained after biogas production are suitable substrates and vectors for NRB. We show that indigenous NRB in digestates grew to high abundance during anaerobic enrichment under N₂O. Gas-kinetics and meta-omic analyses showed that these NRB’s, recovered as metagenome-assembled genomes (MAGs), grew by harvesting fermentation intermediates of the methanogenic consortium. Three NRB’s were isolated, one of which matched the recovered MAG of a Dechloromonas, deemed by proteomics to be the dominant producer of N₂O-reductase in the enrichment. While the isolates harbored genes required for a full denitrification pathway and could thus both produce and sequester N₂O, their regulatory traits predicted that they act as N₂O sinks in soil, which was confirmed experimentally. The isolates were grown by aerobic respiration in digestates, and fertilization with these NRB-enriched digestates reduced N₂O emissions from soil. Our use of digestates for low-cost and large-scale inoculation with NRB in soil can be taken as a blueprint for future applications of this powerful instrument to engineer the soil microbiome, be it for enhancing plant growth, bioremediation, or any other desirable function.Subject terms: Environmental sciences, Environmental microbiology     

衢州市胡柚种植生态适宜性分析

胡柚是衢州市具有原产地域保护的质优产高的特色水果.胡柚种植适宜性区划研究对于区域农业经济发展具有重要意义.本文基于衢州区域内的地理数据、土壤数据和1971-2008年的日常规气象数据,分析了胡柚产量与气象要素关系,建立了胡柚种植的综合区划指标,采用层次分析法建立了胡柚种植的综合区划评估模型.结果表明:衢州市胡柚种植适宜区面积占评价区域的65.47％,较适宜区种植面积占13.12％,不适宜区种植面积占21.41％;区划结果可为衢州市胡柚种植的优化布局和良种结构的调整提供科学依据.     

Waste treatment and biogas quality in small-scale agricultural digesters

Seven low-cost digesters in Costa Rica were studied to determine the potential of these systems to treat animal wastewater and produce renewable energy. The effluent water has a significantly lower oxygen demand (COD decreased from 2968 mg/L to 472 mg/L) and higher dissolved nutrient concentration (NH₄-N increased by 78.3% to 82.2 mg/L) than the influent water, which increases the usefulness of the effluent as an organic fertilizer and decreases its organic loading on surface waters. On average, methane constituted 66% of the produced biogas, which is consistent with industrial digesters. Through principle component analysis, COD, turbidity, NH₄-N, TKN, and pH were determined to be the most useful parameters to characterize wastewater. The results suggest that the systems have the ability to withstand fluctuations in the influent water quality. This study revealed that small-scale agricultural digesters can produce methane at concentrations useful for cooking, while improving the quality of the livestock wastewater.     

Model-based predictions of anaerobic digestion of agricultural substrates for biogas production

A modified Anaerobic Digestion Model No. 1 (ADM1), calibrated on a laboratory digester with a feeding mix of 30% weight of cow manure and 70% weight of corn silage, was implemented, showing its performances of simulation as a decision-making and planning-supporting tool for the anaerobic digestion of agricultural substrates. The virtual fermenter obtained was used to conduct simulations with different feeding compositions and loading rates of cow manure, corn silage, grass silage and rape oil. All simulations were started at the same initial state which was represented by a steady state with an organic loading rate of 2.5 kg ODM/(). The effects of the different feeding combinations on biogas composition and biogas yield were predicted reasonably, and partly verified with the available literature data. Results demonstrated that the simulations could be helpful for taking decisions on agricultural biogas plant operation or experimental set-ups, if used advisedly.     

A conceptual framework for ecosystem stoichiometry: balancing resource supply and demand

The development of ecological stoichiometry has centered on organisms and their interactions, with less emphasis on the meaning or value of a comprehensive ecosystem stoichiometry at larger scales. Here we develop a conceptual framework that relates internal processes and exogenous factors in spatially- and temporally-linked ecosystems. This framework emerges from a functional view of ecosystem stoichiometry rooted in understanding the causes and consequences of relative stoichiometric balance, defined as the balance between ratios of resource supply and demand. We begin by modifying a graphical model based on resource ratio competition theory that relates resource supply and demand to ecosystem processes. This approach identified mechanisms, or stoichiometric schemes, through which ecosystems respond to variable resource supply. We expand this view by considering the effects of exogenous factors other then resource supply that comprise a stoichiometric template that influences stoichiometric balance within ecosystems. We then describe a number of examples of patterns in organismal stoichiometry in several types of ecosystems that illustrate stoichiometric schemes and factors that impinge directly on stoichiometric patterns. Next, we conduct an initial analysis of the stoichiometric effects of spatial linkages between ecosystems, and how those relate to boundary dynamics and hot spot development. We conclude by outlining research directions that will significantly advance our understanding of stoichiometric constraints on ecosystem structure and function.     

松嫩草原区不同农业生态系统土壤动物群落特征

对温带松嫩草原区不同农业生态系统土壤动物群落特征进行了研究。结果表明 ,不同农业生态系统中 ,类群数为草地 >杨树林 >玉米田 ,个体数为草地 >玉米田 >杨树林。土壤动物的垂直分布存在一定差异性。玉米田土壤动物向下层聚集 ,草地具明显的表聚性 ,杨树林随着土层深度的变化较均匀。土壤动物群落的季节变化不同 ,玉米田秋季作物收割后 ,土壤动物类群明显减少 ,而杨树林秋季有增多趋势。草地土壤动物的季节变化代表了松嫩草原区土壤动物群落分布的特征。土壤动物群落的多样性为草地 >杨树林 >玉米田。分析了土壤动物与地温、土壤自然含水量、p H及土壤养分的相关性。     

Agricultural resource use in an andean coastal ecosystem

Five concurrent systems of agricultural resource management in the Viru Valley in Peru's arid northern coastal plain are discussed as adjustments to microenvironmental variations in soil humidity. Widespread dependence on canal irrigation in an environment characterized by uncertainty in the availability of river water affects the agrarian population in several ways. The upper socioeconomic class has adapted to uncertainty by implementing a deviation-counteracting mechanism (tubular wells) that provides water on demand, giving them flexibility in choice of agricultural activities. Another class of farmers is unable to introduce this mechanism, however, and consequently must depend on a repertoire of inflexible decisions to cope with uncertainty. Each group exploits different opportunity costs to increase economic gain. One pattern provides for expansion, whereas the other at best establishes stability and maintenance. Noncanal techniques permit expansion of cultivation in conditions where canal irrigation is not feasible, thereby improving the overall level of effectiveness of resource use. Alternative techniques do not involve regulatory mechanisms nor do they require complex, interlocking social, economic, and political components. Their presence and persistence in the agricultural system provide variation that may ultimately be amplified as the need to intensify resource exploitation increases in the future.     

Trichinella spiralis in an agricultural ecosystem: transmission in the rat population

Four hundred forty-three Norway rats (Rattus norvegicus) were examined to determine their role in the transmission and maintenance of Trichinella spiralis on a pig farm. Rats, classified by sex and weight, were examined for trichinellosis by peptic digestion of muscle samples. Over a 25-mo period, 188 (42.4%) rats were found to be infected with T. spiralis. The mean intensity of infection was 293.2 larvae per gram (LPG) of muscle; 65 (34.6%) infected rats had intensities of infection greater than 100 LPG. Even in the absence of a known source of infected meat (garbage containing meat scraps or dead animals), the rat population maintained the infection, probably through cannibalism. Population reduction was an effective method for reducing the prevalence of infection within the rat population. Therefore, to reduce the likelihood of transmission of T. spiralis between rats and swine, it is essential that rat populations in a farmyard environment be controlled.     

Sourcing native plants to support ecosystem function in different planting contexts

Current guidance on sourcing native plants to support ecosystem function focuses on the high risk of failure when unsuitable material is used in ecological restoration. However, there is growing recognition that risks may be lower and rewards higher at highly disturbed sites isolated from remnant populations, especially when considering support for pollinators, wildlife, and other ecosystem functions. We developed the first decision support tool using expert opinion to assess suitability of different native plant sources, including horticultural cultivars, in two different planting contexts. We assessed the suitability of 761 sources for 72 commonly sold native species in two different planting contexts (small, isolated, highly disturbed sites vs. large, undisturbed sites near remnant populations). Information on genetic and adaptive backgrounds of sources was strikingly lacking, forcing us to exclude one‐third of sources from our assessment. While only 3% of cultivars received high suitability scores for use in large, undisturbed sites near remnant populations, 52% received high suitability scores in small, isolated, highly disturbed sites. However, nearly 25% of cultivars had floral or leaf traits that differed from wild plants in ways that may compromise their ability to support pollinators and other wildlife. Forbs and cultivars lacking genetic diversity and source information were most likely to have altered traits. We recommend that native plant breeders and sellers work together to ensure ecosystem function, adaptation, and diversity information is available to consumers, that consumers request this information to drive demand, and that researchers further investigate how context influences risks and benefits of different sources.     

农业技术措施对AM真菌群落结构的影响研究进展

农业生态系统中AM真菌多样性丰富,并以独特的群落结构发挥其功能.寄主植物和环境因子对AM真菌群落结构具有重要影响,此外,农业技术措施对农业生态系统中AM真菌群落结构的影响也值得关注.本文系统总结了施肥、灌溉、轮作、间作、土壤耕作、化学药剂等农业技术措施对AM真菌群落结构的影响研究进展,分析了农业技术措施改变AM真菌群落结构的可能机制,探讨了提高农业生态系统中AM真菌多样性的可能途径,提出通过改进施肥体制及其配套技术、增加植物多样性和人工接种AM真菌等可提高农业生态系统中AM真菌多样性;并指出当前存在的问题和今后的研究方向.     

北京市退耕还林生态效益评估

基于北京市退耕还林工程区典型样地调查和北京市林业果树科学研究院多年以来对退耕还林生态系统服务功能的监测数据,依据中华人民共和国国家标准《森林生态系统服务功能评估规范》（GB/T 38582-2020）和中华人民共和国林业行业标准《退耕还林工程生态效益监测与评估规范》（LY/T 2573-2016）,分别从涵养水源、固碳释氧、保育土壤、林木积累营养物质、净化大气环境和保护生物多样性六项功能指标,对退耕还林生态效益物质量与价值量进行定量评估。结果表明,截至2018年,北京市退耕还林生态系统服务功能总价值量为18.92亿元/a,其中以涵养水源（41.15%）、固碳释氧（26.73%）和净化大气环境（17.27%）分项指标的贡献作用较大。比较北京市退耕还林工程行政区间生态效益价值量大小,发现退耕面积和北京城市总体规划中各行政区功能定位为主要影响因素,其中以密云区价值量最大为4.48亿元/a,占北京市退耕还林生态系统服务功能总价值量的25.56%。退耕工程区内板栗（29.51%）、仁用杏（13.54%）、核桃（12.57%）所贡献的生态系统服务功能价值量位列前三。不同林分类型单位面积价值量排序为生态林 > 生态经济兼用林 > 鲜果林。因此,建议遵循生态优先、适地适树、分类施策的原则,制定退耕还林成果保护政策,并根据各行政区生态价值评估结果确定生态补偿额度和补偿年限,为退耕还林分类补偿政策制定、低质低效林分改造和退耕还林生态系统监测网络体系奠定理论与实践基础。     

我国HEV废旧镍氢电池包中稀贵金属资源化利用环境效益分析

废旧动力电池包中含有丰富的镍、钴、稀土等稀贵金属,其资源化利用是实现混合动力汽车(Hybrid Electrical Vehicle,简称HEV)全生命周期绿色化管理的重要内容之一。随着HEV的不断发展,动力电池包在未来几年将逐渐进入批量报废阶段,其资源化利用的环境效益成为值得关注的问题。鉴于此,以丰田混合动力汽车镍氢电池包为研究对象,利用GREET模型和LIME值法测算出,相比于原生矿开采,单位废旧镍氢电池包中稀贵金属资源化利用所产生的环境效益为1083元;根据报废周期,对我国市场上现存的HEV镍氢电池包的未来报废情况进行预测。结果表明,这些电池包将从2018年开始迎来报废,在2021年达到报废高峰,至2024年基本完成报废;预计其稀贵金属资源化利用的环境效益,可累计达9421万元。提出了加强废旧动力电池回收体系和资源化利用体系建设的政策建议。